135i low coolant- no cause found

[nkmu]

My 2013 135i DCT has about 30,000 miles. Two months ago it was due for a vehicle check. Everything was fine, except my rear tires...

Last week when I turned on my car I got a low coolant warning. Thinking it strange, I turned it off and then back on, and the warning was gone. Just in case there was a problem, I drove my other vehicle. A few days later I drove the car again and had no warning. It did not overheat. The next time I got in the car I got a low coolant warning again. I did some research on this site and others and found it was fairly common with ambient temp changes (which we've had) and parking on an incline (which I did). I assumed it just needed topped off, but when I checked the coolant it was very low. I called the dealer and the service tech told me to add some water and bring it in.

Today they called me and said "we did a pressure test for two hours and found no leak." He said the coolant was fine and didn't need to be changed despite the amount of water I had to add. My SA said they didn't change the coolant at my last vehicle check, and that the coolant level was fine then.

Attached is a pic of the coolant level (not that helpful I fear) and of how much water I had to add to bring the coolant above the "low" level. Both one-gallon distilled water jugs in the picture were unopened. The one on the left shows how much water I had to add.

This seems like a lot of lost coolant to me. Am I off base on that? It seems like a lot of coolant to lose by evaporation or whatever, especially since the coolant was (supposedly) normal when they checked in July.

Ideas?

[champignon]

Obviously, who can know? Was it really full before even though someone noted it to have been that way on a prior service?

With a 2013 you probably have another 1.5 to 2 years of warranty left. Keep an eye on it and if the problem recurs, then you have a problem. If it does not, then it was a fluke of some sort.

[iminhell1]

No idea if this applies but,
As a precaution I was looking at RockAuto and how much a water pump costs for a 2009. In the notes the Gates pump mentioned something about the design and the weep hole, about how it may drip occasionally and this is intended and should evaporate once the engine is warm. (not verbatim)
Maybe that applies to factory pumps and the N55 also?

If so, checking how much is coming through the weep hole would be a good idea.

[brocklanders]

I had this same thing on my 2013, but at about 15k miles. The dealer filled it I asked if it was something I should be concerned about and they said no. It has to be burning coolant it definitely wasn't leaking anywhere. I have 22k on it now and hasn't happened again yet. I thought it was strange, I had an 11 335 before this car and never experienced such a thing.

[nkmu]

Thanks all. So far it's been fine.

[Silenus]

BMW engines burn coolant, but none more than the N55. This is completely normal, and no damage has been done. Check your coolant level at a more frequent interval.

[1smokehouse]

Had the same thing at round 9k, dealer said to just top it off, so I forked out the $$ for BMW coolant and bought an extra one. Said it was normal in hot climates.

[TwinTurboXI]

I refill my coolant every other month it seems, I have yet to fnd a leak.

[awns729]

I lose a little too - not as much as you - and i was worried about it, so seeing this thread makes me feel better. I've read somewhere that some people prefer it at the low mark to slightly reduce the pressure in the system for increased life of the plastic tank and fill cap's seal.

[jaye944]

you really should'nt loose coolant, it's burning (or boiling) or leaking and depending on how much your loosing is a problem, forget BMW's this is a general car thing,

1) sealed system, has the system been properly bled/burped, so that the level is correct
2) IS it leaking, I heard tell of a weep hole, you need to crawl over the car and see if there are any wet spots OR drips under the car
3) HeadGasket; if there is a leak there the water is mixing with the oil, sometimes you will get mayonnaise in the oil filler (if its really bad), sometimes not, get a HG test kit, fits over the radiator/filler and checks for CO also smell the radiator see if you can smell petrol type smells (not accurate)
4) is there a lot of water dripping from the exhaust pipe (NOT from cold)

[1smokehouse]

Originally Posted by jaye944

you really should'nt loose coolant, it's burning (or boiling) or leaking and depending on how much your loosing is a problem, forget BMW's this is a general car thing,

1) sealed system, has the system been properly bled/burped, so that the level is correct
2) IS it leaking, I heard tell of a weep hole, you need to crawl over the car and see if there are any wet spots OR drips under the car
3) HeadGasket; if there is a leak there the water is mixing with the oil, sometimes you will get mayonnaise in the oil filler (if its really bad), sometimes not, get a HG test kit, fits over the radiator/filler and checks for CO also smell the radiator see if you can smell petrol type smells (not accurate)
4) is there a lot of water dripping from the exhaust pipe (NOT from cold)

Not sure I fully agree. I remember reading somewhere that the thermostat opens fully at 105 Deg C to cool the system - controlled by DME, therefore running hotter than average engines for better thermal efficiency - fuel economy - leaner burning and ignition under normal load. This may account for accelerated evaporation.

I also know my car takes twice as long to cool down than my Volvo did...

However, losing coolant quickly is never a good thing and shouldn't be confused with normal evaporation.

[jaye944]

Usually an engine at its ordinary working temperature the water coolant is only just below normal boiling point 100deg. To stop the water/coolant from boiling over you add water/af mix also increasing the pressure in the system, raises the boiling point.

The pressure is limited by the radiator cap, which has a pressure valve in it. Excessive pressure opens the valve, and coolant flows out through an overflow pipe. to "somewhere" older cars it would drip on the road, my first Capri did this, but it's not envoirenmentally friendly right

So that's why in a older cooling system there is a continual slight loss of coolant if the engine runs very hot. The system needs topping up from time to time.

Newer cars have a sealed system in which any overflow goes into an expansion tank, from which it is sucked back into the engine when the remaining liquid cools. ergo; you should not need to continually top up fluid.

I never had to "top-up" water in any car newer than 1991 for this reason
Fords , Chevvy, GM, Porsche

Originally Posted by 1smokehouse

Not sure I fully agree. I remember reading somewhere that the thermostat opens fully at 105 Deg C to cool the system - controlled by DME, therefore running hotter than average engines for better thermal efficiency - fuel economy - leaner burning and ignition under normal load. This may account for accelerated evaporation.

I also know my car takes twice as long to cool down than my Volvo did...

However, losing coolant quickly is never a good thing and shouldn't be confused with normal evaporation.

[brocklanders]

I'm not sure what to think, this is my second n55 I had a 2011 335 and put 30k miles on her and never had to top off the coolant. Now with this 2013 135 it was low at around 9 or 10k can't remember exactly. I still have three years left on my finance option so I guess if it keeps up I may get rid of it, it will be a sad day, its been awhile since I felt this way about a vehicle but I've done the out of warranty BMW thing before and its not much fun.

[nkmu]

Originally Posted by brocklanders

I'm not sure what to think, this is my second n55 I had a 2011 335 and put 30k miles on her and never had to top off the coolant. Now with this 2013 135 it was low at around 9 or 10k can't remember exactly. I still have three years left on my finance option so I guess if it keeps up I may get rid of it, it will be a sad day, its been awhile since I felt this way about a vehicle but I've done the out of warranty BMW thing before and its not much fun.

I'm wondering what I'll do when my warranty is up too. I don't want big expenses, but most fixes are cheaper than a new car...

I don't know what I'd want either. 2 series- more of the same. Bigger BMW- too $$$, and I like small cars. Miata- love love love them, but probably too small. C7- wife says they're only for old men.

[brocklanders]

Originally Posted by nkmu

I'm wondering what I'll do when my warranty is up too. I don't want big expenses, but most fixes are cheaper than a new car...

I don't know what I'd want either. 2 series- more of the same. Bigger BMW- too $$$, and I like small cars. Miata- love love love them, but probably too small. C7- wife says they're only for old men.

I'm leaning towards leasing a ford focus. ...... and an e36 m3 for a garage queen.

[SirSmokeAlot]

Noticing my car Drinking Coolant. What should I do?

[jdt10768]

top it up, and monitor weekly for a while

[tracer bullet]

Originally Posted by jdt10768

top it up, and monitor weekly for a while

Agreed for sure.

I'd add look under the car for any dripping, and monitor the exhaust for any white "smoke".

[SirSmokeAlot]

Sounds good, and will do.. Not seeing any traces of leakage where it was parked. But yea, I will check it regularly, I have not owned it that long, previous owner said he just had the water pump replaced not long ago.

[tracer bullet]

Originally Posted by SirSmokeAlot

just had the water pump replaced not long ago.

There's a decent chance it wasn't completely filled at the time.

Also a chance of a leak as well of course, unfortunately. The parts that get replaced are nearish to the passenger headlight, but with the plastic undertray it could come out anywhere and it might even be a little while before it does, or even after you start driving.

Are you a handy person? You could get the front of the car up in the air and unscrew all the little bolts that hold that plastic undertray on, remove it for a while, and then actually get a look at what's up. Directly at the pump, t-stat, and hoses right away, and then also be sure that if it is leaking it'll definitely hit the ground right underneath and not get trapped and fool you.

I'd start with ensuring it's full, though. Fill it up and then run the bleed procedure at least once. You'll need to search for it but it's somethign along the lines of inserting the key and holding the gas pedal down 10 seconds. That might actually be all it is. You'll hear some whining as the pump turns on. You can take the fill cap off and see it squirting in the reservoir.

[SirSmokeAlot]

Yea, thanks for the advice, I appreciate it. I don't drive it every day so I'll try to look into what you are saying. So it can be leaking and not hitting the ground in a sense?

[SirSmokeAlot]

Most of all just going to monitor it for a few weeks, see if I have to keep adding more, at which point. Will have to find the cause.